The strike comes just as tensions deepened between the U.S. and Pakistan over a Pakistani doctor who was sentenced to 33 years in prison for treason after helping find Usama bin Laden.

Dr. Shakil Afridi ran a vaccination program for the CIA to collect DNA and verify bin Laden's presence at the compound in the town of Abbottabad where U.S. commandos killed the Al Qaeda chief in a May 2011 raid.

The operation outraged Pakistani officials, who portrayed it as an act of treachery by a supposed ally.

But a senior U.S. official with knowledge of counter-terrorism operations against Al Qaeda in Pakistan said the doctor was never asked to spy on Pakistan.

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Two officials say Thursday's drone attack took place in a militant hideout in Khassokhel village near Mir Ali in the North Waziristan tribal area. It was the second such attack in 24 hours in the region.

The officials say most of those killed were Uzbek insurgents. They spoke on condition of anonymity because they were not authorized to talk to the media.

Drone strikes have become an increasingly contentious issue between the U.S. and Pakistan.

Pakistan's Parliament recently demanded the U.S. end all drone strikes on its territory. The U.S. has shown no intention of stopping the covert CIA program.